1. Field of the Invention
This invention relates to a vapor emission control system for preventing the atmospheric escape of vapors generated during the liquid filling of a fuel tank.
More particularly, this invention relates to a method and apparatus for recapturing and controlling the vapor emission generated in motor vehicles during fuel tank filling.
A problem of long standing in the art has to deal with escaping vapors when transferring volatile liquids from a liquid source to a receiving tank. Vapors from the transferred fluid are generated because of elevated ambient temperatures, the volatility of the fluid, and kinetic energy imparted to the liquids being transferred. Additionally, receiving tank vapors seek container escape when displaced by the transferred liquid volume.
This problem has become particularly acute in recent years because of the increased legislative concern for environmental purification and the related energy crisis. Proposed legislation would require completely closed service station systems and/or closed automobile fuel systems. The present cost of satisfactory vapor recovery systems for service stations is extremely expensive.
2. Description of the Prior Art
Because of the aforementioned recognized art problem, various apparatus and operational methods have been developed to preclude vapor loss and noxious dissemination into the atmosphere. The most pertinent prior art to that disclosed by the instant invention relates to vapor emission control systems wherein the vapors are transferred to a separate holding tank for adsorbent storage and/or conventional scrubbing.
Representative of this art is a patent issued to G. Torazza, U.S. Pat. No. 3,695,243 wherein the displaced vapors are vapor drawn through a multiple vapor collection manifold into an air purged, activated carbon containing vapor trap. This reference, however, does not employ a vacuum accumulator.
Another vapor recovery apparatus is described in a patent issued to G. R. Onufer, U.S. Pat. No. 3,581,782. One embodiment of the Onufer patent provides as shown therein at FIG. 2 for fuel tank displaced vapors to be transferred via a fluid return line to a complicated, stationary, intermediate activated filter container which serves as a conventional scrubbing canister. Although a carburetor vacuum withdraws vapor from the canister, it does so only when the engine is running and then from an open system wherein air is passed upwardly through the activated charcoal.